In recent years, an image pickup device employs a technology, wherein a movable portion for holding an image pickup lens is moved by utilizing the shape restoring ability of a shape memory alloy to position the image pickup lens. A shape memory alloy, however, has a drawback that it is impossible to start moving a movable portion immediately after start of energization of a shape memory alloy member, because the shape memory alloy member is not deformed unless heated over a predetermined temperature. Patent literature 1 discloses an improved technology, wherein the response speed of a movable portion is increased by energizing a shape memory alloy member in a standby state before start of driving the movable portion to a targeted position.
However, in the case where a movable portion is positioned by utilizing the shape restoring ability of a shape memory alloy, positional displacement may occur resulting from e.g. a change in the characteristic of the shape memory alloy due to a change in the ambient temperature or deterioration of the shape memory alloy, or deterioration of a moving mechanism portion for moving the movable portion. Accordingly, it has been difficult or impossible to apply a shape memory alloy to a device that requires positional precision, particularly an image pickup device designed such that an image pickup lens is required to be positioned to a standby position with high precision.
Patent literature 1: JP 2001-263221A